Autosomal Dominant Retinitis Pigmentosa Families Research Articles

Identification of a novel RHO heterozygous nonsense mutation in a Chinese family with autosomal dominant retinitis pigmentosa

BackgroundTo explore the molecular genetic cause of a four-generation autosomal dominant retinitis pigmentosa family in China.MethodsTargeted region sequencing was performed to detect the potential mutation, and Sanger sequencing was used to validate the mutation. Multiple sequence alignment from different species was performed by CLUSTALW. The structures of wild-type and the mutant RHO were modeled by Swiss-Model Server and shown using a PyMOL Molecular Graphic system.ResultsA novel heterozygous nonsense mutation (c.1015 A > T, p.Lys339Ter, p.K339X) within RHO, which cosegregated with retinitis pigmentosa phenotype was detected in this family. Bioinformatics analysis showed the mutation was located in a highly conserved region, and the mutation was predicted to be pathogenic.ConclusionsWe identified a novel heterozygous nonsense mutation of RHO gene in a Chinese family with retinitis pigmentosa by target region sequencing and our bioinformatics analysis indicated that the mutation is pathogenic. Our results can broaden the spectrum of RHO gene mutation and enrich the phenotype-genotype correlation of retinitis pigmentosa.

Detection and analysis of the Rhodopsin gene in a consanguineous Chinese Han autosomal dominant retinitis pigmentosa family

Background Rhodopsin (RHO) gene is the most common disease gene for autosomal dominant retinitis pigmentosa (adRP),one of the main pathogenesis is that misfolded mutant RHO proteins accumulate in the endoplasmic reticulum and cause endoplasmic reticulum stress (ERS).Objective This study aimed to determine the genetic basis for a consanguineous Chinese Han adRP family.Methods This study procedure complied with Helsinki Declaration.All participants in the family were investigated under the informed consent.Regular ocular examination was performed on the patients in this family.Next-generation sequencing (NGS) was carried out to screen the mutations in 189 genes associated with hereditary retinal diseases (HRDs).After being analyzed and filtered,variations detected by NGS were validated by Sanger sequencing and evaluating of pathogenicity.The wild-type RHOWT and mutant RHOP53Rwere cloned into the vector pEGFP-N1.Then the two plasmids were transfected into adult retinal pigmentosa epithelium cell line(ARPE19) and human embryo kidney 293 line (HEK293) to observe the location of rhodopsin-GFP fusion protein in cells,and the expression of ERS related protein XBP1 in the cells was detected by quantitative-PCR and Western blot.Results This family included 5 generations with the typical adRP characteristics.Genetic analysis identified a heterozygous variation,p.P53R in RHO gene,which was fully cosegregated in the family.Wild-type RHOWT-GFP fusion proteins showed the green fluorescence on the endoplasmic reticulum and cytomembrane,but the misfolded mutant RHO-GFP fusion protein gathered only in endoplasmic reticulum.Compared to wild-type RHOWT,the XBP1 was activated and increased by (1.28 ±0.09) fold.The introns of 26 bases in XBP1 mRNA were removed in the HEK293 cells with mutant RHO-GFP fusion protein,and the expression of XBP1 was stronger in the HEK293 cells with mutant RHO-GFP than that in HEK293 cells with wild type RHO-GFP and cells with blank pEGFP-N1 plasmid.Conclusions Heterozygous variant RHO p.P53R is very likely the pathogenical mutation in the adRP family.The RHOP53R mutant rhodopsin protein can not be delivery effectively from the endoplasmic reticulum to the cell membrane,and these proteins accumulate in the endoplasmic reticulum,which causes ERS. Key words: Autosomal dominant retinitis pigmentosa; Rhodopsin; Next-generation sequencing; Endoplasmic reticulum stress

Linkage analysis and mutation screening of candidate gene in a Han Nationality family with autosomal dominant retinitis pigmentosa

Background Retinitis pigmentosa (RP) has the genetic and phenotype heterogeneity.To determine the disease-causing gene is a foundation of gene therapy. Objective This study was to localize the pathogenic gene and screen the gene mutation associated with Han Nationality autosomal dominant retinitis pigmentosa (ADRP) in a Chinese family. Methods Twenty-one families enrolled this study,including 12 patients with ADRP and 9 individuals with normal phenotype.Perimetry,fundus examination,electrooculogram ( EOG ) and electroretinogram (ERG) were performed in 12 patients.Genetic linkage analysis was performed on the subjects in all known genetic loci related to ADRP with a panel of microsatellite markers.Subsequently,the mutation screening of rhodopsin gene was screened by direct DNA sequencing.This study was approved by Ethic Committee of Zhongnan Hospital of Wuhan University.Informed consent was obtained from each subject. Results The fundus appearance of the proband was in accordance with the ADRP,and the EOG and ERG showed undetectable.Contractive visual field also was exhibited in the proband.Linkage analysis showed that the maximum logarithm of the odds(LOD) score reached 3.6671 at marker D3S1292 at recombination fraction θ =0.0.The results of direct DNA sequencing revealed a C→ G transversion mutation at codon 53 in exon 1 of rhodopsin gene,which resulted in a proline to arginine change (Pro53Arg) in 12 patients.However,no similar mutation was found in the unaffected members of this family.Conclusions The missence mutation Pro53Arg in rhodopsin gene cosegregate with the RP disease.It is determined to be a pathogenic factor of this ADRP family. Key words: Retinitis pigmentosa; Inheritance; Linkage analysis; Cene mutation; Rhodopsin

Novel PRPF31 and PRPH2 Mutations and Co-occurrence of PRPF31 and RHO Mutations in Chinese Patients With Retinitis Pigmentosa

To screen mutations in the PRPF31, RHO, and PRPH2 genes in Chinese patients with retinitis pigmentosa (RP). Patients with RP were recruited from Retina Hong Kong. All the exons of the PRPF31, RHO, and PRPH2 genes were amplified and screened for mutations using single-stranded conformation polymorphism analysis followed by DNA sequencing. Frequencies of sequence changes were determined in patients and controls. In 76 patients from 54 families, 3 pathogenic mutations and 32 nonpathogenic sequence changes were identified. One family with autosomal dominant RP was found to harbor a novel truncating PRPF31 mutation (p.Phe262SerfsX59) and a known missense RHO mutation (p.Pro347Leu), and 1 affected woman was heterozygous for both mutations. One simplex RP case was caused by a novel truncating PRPH2 mutation (p.Ala78LeufsX99). Thirteen of the 32 nonpathogenic sequence changes were novel and were found in low frequencies in patients with RP and controls. Mutations in PRPF31, RHO, and PRPH2 were found in low frequencies (1 of 9 autosomal dominant RP families) in Chinese patients, and the PRPF31 and PRPH2 truncating mutations were novel. A search for a common cause for RP in Chinese patients is needed. The co-occurrence of 2 different gene mutations may modify the phenotype severity.

Attitudes Regarding Predictive Testing for Retinitis Pigmentosa

Purpose: To assess attitudes towards predictive testing for autosomal dominant retinitis pigmentosa (ADRP). Methods: A prospective questionnaire study of 46 affected adults and their adult family members identified from pedigrees clearly consistent with ADRP or who had had DNA-testing confirmation of ADRP before the study commenced. Results: High proportions of unaffected siblings (73%) and patients (67%) agreed to prenatal testing. Patients agreed to prenatal testing. Patients agreed significantly more often than unaffected siblings that treatment should be available prior to initiating predictive testing. Psychoemotional distress was reported in 57% of the affected adults and their family members in recollecting their own predictive testing as children. Conclusions: ADRP families indicate a favorable attitude towards testing presymptomatic children with counseling to lessen the psychological and social impact of results.

Clinical Phenotype of an Italian Family with a New Mutation in the PRPF8 Gene

To report the clinical and functional characteristics of an autosomal dominant retinitis pigmentosa (ADRP) family with a novel point mutation (P2301S) in the PRPF8 gene. PRPF8 gene analysis and complete ophthalmologic examination in an ADRP family. Clinical examination revealed the typical RP phenotype in all family members. Electroretinography showed preserved ERG photopic responses. Genetic analysis showed that the P2301S missense mutation segregated with the disease in all subjects. Unlike previously reported families, the PRPF8 gene mutation in our family is associated with a mild phenotype in which cone function is partially preserved.

Spectrum and Frequency of Mutations in IMPDH1 Associated with Autosomal Dominant Retinitis Pigmentosa and Leber Congenital Amaurosis

The purpose of this study was to determine the frequency and spectrum of inosine monophosphate dehydrogenase type I (IMPDH1) mutations associated with autosomal dominant retinitis pigmentosa (RP), to determine whether mutations in IMPDH1 cause other forms of inherited retinal degeneration, and to analyze IMPDH1 mutations for alterations in enzyme activity and nucleic acid binding. The coding sequence and flanking intron/exon junctions of IMPDH1 were analyzed in 203 patients with autosomal dominant RP (adRP), 55 patients with autosomal recessive RP (arRP), 7 patients with isolated RP, 17 patients with macular degeneration (MD), and 24 patients with Leber congenital amaurosis (LCA). DNA samples were tested for mutations by sequencing only or by a combination of single-stranded conformational analysis and by sequencing. Production of fluorescent reduced nicotinamide adenine dinucleotide (NADH) was used to measure enzymatic activity of mutant IMPDH1 proteins. The affinity and the specificity of mutant IMPDH1 proteins for single-stranded nucleic acids were determined by filter-binding assays. Five different IMPDH1 variants, Thr116Met, Asp226Asn, Val268Ile, Gly324Asp, and His 372Pro, were identified in eight autosomal dominant RP families. Two additional IMPDH1 variants, Arg105Trp and Asn198Lys, were found in two patients with isolated LCA. None of the novel IMPDH1 mutants identified in this study altered the enzymatic activity of the corresponding proteins. In contrast, the affinity and/or the specificity of single-stranded nucleic acid binding were altered for each IMPDH1 mutant except the Gly324Asp variant. Mutations in IMPDH1 account for approximately 2% of families with adRP, and de novo IMPDH1 mutations are also rare causes of isolated LCA. This analysis of the novel IMPDH1 mutants substantiates previous reports that IMPDH1 mutations do not alter enzyme activity and demonstrates that these mutants alter the recently identified single-stranded nucleic acid binding property of IMPDH. Studies are needed to further characterize the functional significance of IMPDH1 nucleic acid binding and its potential relationship to retinal degeneration.

Mutational analysis of the rhodopsin gene in Chinese ADRP families by conformation sensitive gel electrophoresis

Retinitis pigmentosa is a very heterogeneous group of retinal degenerations, with multiple genes identified in each mode of inheritance. For autosomal dominant retinitis pigmentosa (ADRP), the most common gene is the rhodopsin (RHO) gene, mutations in which contribute to about 25% of ADRP in Caucasian population. To investigate the frequency and pattern of RHO point mutations in Chinese patients with ADRP, we have screened the five coding exons and splice sites of the RHO gene in 50 unrelated probands from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. Two RHO mutations, Pro347Leu and Pro327 (1-bp del), were identified each in one family, thus the frequency of RHO mutations among ADRP families in this study is less than 14% (2 / 50 = 4%, 95% confidence interval: 1–14%), lower than that in Europe and North America, which may reflect an ethnic difference between Chinese and Caucasian populations. Loss of all phosphorylation sites at the C-terminus and a highly conserved sequence QVS(A)PA may occur because of Pro327(1-bp del). CSGE was found to be a sensitive, simple and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.

Novel rhodopsin mutation in a Chinese family with autosomal dominant retinitis pigmentosa

Purpose: To identify mutations in the rhodopsin ( RHO ) gene in Chinese patients with autosomal dominant retinitis pigmentosa (ADRP) and to measure the prevalence rate of RHO mutations in Chinese ADRP cases. Methods: Thirteen Chinese families with ADRP were clinically characterized. The complete coding region and intron splice sites of RHO were analyzed for mutations with single-strand conformation polymorphism (SSCP) analysis and direct genomic sequencing. Results: One of the 13 Chinese families with ADRP was found to have a new, previously unidentified RHO mutation, a change from GAG to TAG at codon 341. The mutation (E341X) results in an in-frame stop codon, leading to the truncation of the rhodopsin protein. Mutation E341X was not detected in 100 normal control individuals. Patients carrying mutation E341X reported night blindness and showed optic atrophy, vessel attenuation, and a few bone spicule-like pigments in peripheral retina at the age of 23–25 years. At the age of 30 years, visual acuity was severely impaired, peripheral visual field was greatly constricted, rod and cone ERG was not detectable, and only a slight left cone response remained. Conclusion: We have identified a novel rhodopsin mutation (E341X) in a Chinese family with ADRP. The location and character of the mutation expand the spectrum of RHO mutations causing RP. Identification of a RHO mutation in one of the 13 ADRP families studied suggests that only 7.7% of the ADRP cases in a Chinese population were caused by RHO mutations, a ratio significantly lower than that from North America or Europe.

Exclusion of CAG repeat expansion as the cause of disease in autosomal dominant retinitis pigmentosa families.

The involvement of genes with expanded tracts of (CAG)n in some neurodegenerative diseases is well established. Whether genes containing these motifs could also have a role in degenerative diseases affecting...

Linkage of a medium sized Scottish autosomal dominant retinitis pigmentosa family to chromosome 7q.

Retinitis pigmentosa is a group of hereditary retinopathies which is both clinically and genetically heterogeneous. Autosomal dominant (ADRP), autosomal recessive (ARRP), and X linked recessive (XLRP), as well as digenic forms of inheritance have been reported. ADRP has been linked to 3q, 6p, 7p, 7q, 8cen, 17p, 17q, and 19q. Three unrelated ADRP families have been reported to show linkage to 7q. We tested a Scottish ADRP family with microsatellite markers mapping within the 7q31-q35 region, and found three markers (D7S487, D7S514, D7S530) showing statistically significant evidence of linkage. A maximum two point lod score of 3.311 at 0% recombination was obtained for D7S514.

Novel rhodopsin mutation in an autosomal dominant retinitis pigmentosa family: phenotypic variation in both heterozygote and homozygote Val137Met mutant patients.

A family affected with autosomal dominant retinitis pigmentosa (RP) is presented. Two clinically affected patients (mother and daughter) were heterozygous for the same novel missense mutation (Val137Met) of the rhodopsin gene (RHO). Both heterozygous and homozygous cases were observed among their few symptomatic relatives. Wide clinical variation was exhibited among the individuals with mutations in this family. None of the controls showed this change in RHO, nor has it been previously reported in other RP families. No other RHO mutation was observed. Additional genetic or environmental factors could play a role in modulating the penetrance and clinical expression of this RHO mutation.

G106R rhodopsin mutation is also present in Spanish ADRP patients.

A large family affected with autosomal dominant retinitis pigmentosa (ADRP) with a sectorial phenotype showed a previously described (G to A) mutation in the rhodopsin gene resulting in the substitution of a glycine residue by an arginine in codon 106 of rhodopsin. This mutation shows some unusual characteristics, such as initial pathology of the inferior retina, superior visual field with normal disc and retinal vessels, and ERG findings that show a modest reduction in both cone and rod amplitudes with normal implicit times. The Gly 106 Arg mutation has been previously reported in American and British patients. Its presence in a Spanish ADRP family confirms that it and its homogeneous associated phenotype are geographically widespread.

Gly114Asp mutation of rhodopsin in autosomal dominant retinitis pigmentosa

Two autosomal dominant retinitis pigmentosa families of different origin were screened for rhodopsin mutations using the method of single strand conformation polymorphism and direct sequencing. We found a CGG-CAG substitution in codon 114 of rhodopsin in both families. This change predicted the replacement of a glycine by an aspartic acid and suggested that this change is the cause of the disease in these families.

A missense mutation (211His-Arg) and a silent (160Thr) mutation within the rhodopsin gene in a Spanish autosomal dominant retinitis pigmentosa family

A missense mutation (211His-Arg) and a silent (160Thr) mutation within the rhodopsin gene in a Spanish autosomal dominant retinitis pigmentosa family

Linkage mapping of autosomal dominant retinitis pigmentosa (RP1) to the pericentric region of human chromosome 8

Linkage mapping in a large, seven-generation family with type 2 autosomal dominant retinitis pigmentosa (ADRP) demonstrates linkage between the disease locus (RP1) and DNA markers on the short arm of human chromosome 8. Five markers were most informative for mapping ADRP in this family using two-point linkage analysis. The markers, their maximum lod scores, and recombination distances were ANK1 (ankyrin)—2.0 at 16%; D8S5 (TL11)—5.3 at 17%; D8S87 [a(CA) n repeat]—7.2 at 14%; LPL (lipoprotein lipase)—1.5 at 26%; and PLAT (plasminigen activator, tissue)—10.6 at 7%. Multipoint linkage analysis, using a simplified pedigree structure for the family (which contains 192 individuals and two inbreeding loops), gave a maximum lod score of 12.2 for RP1 at a distance 8.1 cM proximal to PLAT in the pericentric region of the chromosome. Based on linkage data from the CEPH (Paris) reference families and physical mapping information from a somatic cell hybrid panel of chromosome 8 fragments, the most likely order for four of these five loci and the diseases locus is 8pter-LPL-D8S5-D8S87-PLAT-RP1. (The precise location of ANK1 relative to PLAT in this map is not established.) The most likely location for RP1 is in the pericentric region of the chromosome. Recently, several families with ADRP with tight linkage to the rhodopsin locus at 3q21–q24 were reported and a number of specific rhodopsin mutations in families with ADRP have since been reported. In other ADRP families, including the one in this study, linkage to rhodopsin has been excluded. Thus mutations at two different loci, at least, have been shown to cause ADRP. There is no remarkable clinical disparity in the expression of disease caused by these different loci.

Autosomal dominant retinitis pigmentosa: Four new mutations in rhodopsin, one of them in the retinal attachment site

Several mutations in the rhodopsin gene in patients affected by autosomal dominant retinitis pigmentosa (ADRP) have recently been described. We report four new rhodopsin mutations in ADRP families, initially identified as heteroduplexed PCR fragments on hydrolink gels. One is an in-frame 12-bp deletion of codons 68 to 71. The other three are point mutations involving codons 190, 211, and 296. Each alters the amino acid encoded. The codon 190 mutation has been detected in 2 from a panel of 34 ADRP families, while the remaining mutations were seen in single families. This suggests that, consistent with a dominant condition, no single mutation will account for a large fraction of ADRP cases. The base substitution in codon 296 alters the lysine residue that functions as the attachment site for 11- cis-retinal, mutating it to glutamic acid. This mutation occurs in a family with an unusually severe phenotype, resulting in early onset of disease and cataracts in the third or fourth decade of life. This result demonstrates a correlation between the location of the mutation and the severity of phenotype in rhodopsin RP.